Re: Warmer tones

Eric J. Neilsen (ejnasn@laplaza.org)
Thu, 01 May 1997 09:49:36 -0600 (MDT)

On Wed, 30 Apr 1997, John Rudiak wrote:
> >
> You claim that this is an equimolar amount relative to the platinum
> solution. It is not. The platinum salt has a formula weight of 413
> gm/M. At a concentration of 200 gm/L (10 gm/ 50ml) the molarity of the
> solution is 0.484. The palladium salt has a formula weight of 292 gm/M.
> Simple math shows that to achieve a molarity of 0.484, we need a
> concentration of 141 gm/L, or 8.5 gm in 60 ml. water. Just 'cause you
> can get more in solution because of higher solubility doesn't mean you
> can use it all. You may just be wasting palladium.
>

While I did make a mistake in my statement of equal molarity, I do stand
by my results. I did these calculations severals years back, and I must
admit that when I did the molar calculations of the 5 grams/3.5 grams
Palladium solution I compared the concentration (.722) to the Ware
Ammonium salts. His concentrations for platinum salt is .68 and palladium
.70. Where using a ferric concentration of 1.4m with his metal salts, a
closely 2:1 ferric to metal salts.

I keeping with that line of thought and the 2:1 molar ratios, I decided to
try the "extra" palladium in my formula. The prints are smoother, warmer
and richer than those made with the formulas that we used in our printing
business.

As furthur evidence of added palladium in the coating solution providing
warmer prints, Several years back when I was working with another
individual, we purchased much palladium from Richard (B&S) in a liquid
form. THis one time our prints turned out MUCH warmer than before. The
palladium looked darker so I weighed some bottles and found that a mistake
had appearently been made by Richard. When I talked to Richard he said
that it was quite possible that he doubled the concentration by accident.
He lost track of what he had added to the bottles. These prints did not
exhibit any chocolate stain that one might get from "free" palladium
chloride, just nice warm prints. This indicated to me that the
concentration of palladium salt (Na2PdCl4) could certainly be increased.

With all the different ferric oxalate being used by printers, I believe
that balancing the molar solution must be a personal choice. I can
state with extreme confidence that the prints that I'm making today with
the formulas that I use give me better prints than your formulas or others
that I have used over the last 15 years.

I think we can all agree that printing is a very individual experience,
and over the years we probably all have tried a little of this and a
little of that to achieve "a better" print.

I use my ferric at a 25% concentration, or Sp Gr. of 1.62 with a pH of .7.
This I make myself. The formula for the metal salts were previously
listed.

Happy Printing!
EJ Neilsen
ejnasn@laplaza.org